Diaphragm or diaphragm mount for loudspeakers or other sound reproducing devices



p 20, 1932- J. BRUIJNES ET AL DIAPHRAGM OR DIAPHRAGM MOUNT FOR LOUD SPEAKERS OR OTHER SOUND REPRODUCING DEVICES Filed July 15. 1927 H INVENTORS Johannes Br'u IJI1S and Arend Thomas van Urk BY other means.

Patented Sept. 20, 1932' UNITED STATES PATENT OFFICE JOHANNES BRUIJNES AND AREND THOMAS VAN URK, OF EINDHOVEN, NETHERLANDS,

ASSIGNORS TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE DIAPHRAGM OR DIAPHRAGM MOUNT FOR LOUDSPEAKERS OR OTHER SOUND REPRO- DUCING DEVICES Application filed July 15, 1927, Serial No. 205,936, and in the Netherlands September 13, 1926.

This invention relates to loudspeakers or like apparatus provided with diaphragms or vibrating members which are supported at their edge for example by baflle. plates or The term baffle plate must be understood to mean a plate which surrounds the edge of the diaphragm or vibrating member so that the free air path between the front and rear sides of the said diaphragm is lengthm ened. In order to ensure satisfactory results,

it is obvious that the edge of the diaphragm should be secured to the plate in such a manner that the diaphragm is free to move without air streaming between the diaphragm and the baffle plate. Due to this air stream, rarefactions and compressions which are caused by the vibrating movement of the diaphragm, will weaken one another, and therefore low tones will disappear from the sound of the loudspeaker and a faithful reproduction is impossible. In a known construction, the diaphragm and the baflle plate are secured to each other by means of a yieldin substance which is fixed to the edge of the diaphragm and to the baffle plate. Besides the difiiculties met with in the manufacture of this construction it also has the disadvantage in that a rustling noise is produced. This noise is caused by the yielding substance moving together with the diaphragm whereby it is bent and produces sound.

According to the invention, the edge of the diaphragm or vibrating member is located between strips of a yielding substance, said strips being secured to a rigid support or to a battle plate. The diaphragm is not secured to these strips but is loosely located between them. The strips are made of textile fabric, preferably of woolen fabric such as flannel or serge, since these substances have the ad vantage of being very supple so that the crackling noise which frequently occurs when leather is used, is not produced.

In an embodiment of the invention a conical diaphragm has been provided, the edge of which is provided with a collar located between strips of woolen fabric. As it is generally difficult to provide the edge of a conical body with a collar, the conical member is made of celluloid, which in combination with the above mentioned special support enables the manufacturer to build a very cheap, reliable and solid sound reproducing device.

The invention will be more clearly understood by referring to the accompanying drawing representing an embodiment of the invention. In this drawing:

Figure 1 is a front view of a loud-speaker provided with a baffle plate having secured 7 In the drawing, 1 is a conical vibrating member which is set in vibration by a style 2 which may be coupled to a magnet system. At its edge, the cone 1 is provided with a ring or collar 8located between flannel strips 3 and 4 which by means of clamping rings 5 and 6 are secured to a baffle plate 7. The construction which is more clearly shown in Figure 3, serves to support the edge of the cone in such a manner that the latter is free to move and practically no air can stream from the fore to the rearside of the vibrating member. The strips preferably are flannel inasmuch as woolen fabrics are very supple and assure a satisfactory obturation.

What we claim is:

1. A loud speaker comprising a vibrating member, a stationary member, and fabric strips each fastened at an edge only to one of said members and loosely in contact at their free portions with opposite sides of the other member.

2. An acoustic device comprising a vibratile member, a stationary member having an edge portion adjacent to the periphery of said vibratile member but out of contact therewith,

and a pair of flat yieldable members fastened to said edge portion on opposite sides thereof, each of said flat yieldable members being fastened to said edge portion so that a part thereof extends freely beyond said edge portion to loosely engage said vibratile member near its periphery.

3. An acoustic device according to claim 2 in which said flat yieldable members consist of strips of textile fabric.

4. An acoustic device according to claim 2 in which said flat yieldable members consist of strips of Wool fabric such as flannel.

5. An acoustic device according to claim 2 in which said vibratile member consists of a conical diaphmgm provided at its edge with a collar which is positioned between said pair of flat yieldable members.

J OHANNES BRUIJNES. AREND THOMAS VAN URK. 

